The present invention relates to a rotary switch and a hand tool machine comprising such a rotary switch, in particular a rotary switch for selecting between two modes of the hand tool machine, e.g., a percussion mode and a drill percussion mode, with a combination hammer.
A rotary switch for actuating an axially slidable switch element of a hand tool machine has been known from European Patent Document No. EP 1 632 314 A2. An eccentrically arranged parable-shaped lug is clamped to a twist handle. A spiral spring is hinged to a pin located outside the twist handle. Two spring legs of the spiral spring enclose the parable-shaped lug. In addition, the two spring legs clamp a projection in place on the axially slidable switch element. When the twist handle is being turned, respectively one of the spring legs is unhinged by the lug against a spring bias while the lug detaches from the other spring leg. The other spring leg exerts a force on the projection until the axially shiftable switch element moves in the lateral direction and the other spring leg abuts again against the lug.
Indeed, with the rotary switch in accordance with EP 1 632 314 A2, it is possible to implement a synchronization of the position of the axially shiftable switch element with the position of the rotary switch, independently of the direction of rotation; however, this involves great effort in assembling the rotary switch because the switch cannot be attached in one piece to the tool machine. Furthermore, the two spring legs must be clamped on when the spiral spring is being mounted.
The object is to provide a rotary switch featuring a simplified assembly option.
The inventive rotary switch for shifting a switch element comprises a twist handle, a torsion spring, a rotatable actuating element and a common axis. The twist handle, the torsion spring and the rotatable actuating element are supported so as to be rotatable about the common axis. The twist handle and the rotatable actuating element are coupled via the torsion spring in such a manner that a relative twisting of the twist handle with respect to the rotatable actuating element twists the torsion spring. An eccentric is provided on the rotatable actuating element in order to convert a rotary motion of the rotatable actuating element into a shifting motion of the switch element.
The rotatable actuating element follows the rotating motion of the twist handle to the extent that the actuating element is not hindered from doing so by the switch element that is coupled to the eccentric. Then the rotatable actuating element and the twist handle again assume a synchronous position. The relative twisting is understood to refer to one of the synchronous positions of the twist handle relative to the actuating element. In the synchronous position, the torsion spring is preferably again in an inoperative position with minimal or no tension. This is possible because the torsion spring can also rotate about the axis of rotation. A mechanical load applied to the rotary switch in a synchronous position may thus be advantageously low.
The common arrangement of the elements on one axis allows a prefabrication of the rotary switch that can then be fastened as one component to a tool machine. In particular, the clamping legs of a spring need not be fastened to a spring of a tool machine.
Considering a further development, the twist handle can be twisted relative to the rotatable actuating element in a negative direction of rotation and relative to the axis of rotation in the positive direction of rotation. The twist handle and the rotatable actuating element, respectively, comprise an abutment that faces in the positive direction of rotation relative to the axis of rotation, and an abutment that faces in the negative direction of rotation relative to the axis of rotation. The torsion spring comprises two engagement elements. The engagement elements are arranged with respect to the abutments in such a manner that, as a result of relative twisting, one engagement element—the element being subjected to a force—couples with one of the abutments of the twist handle, and that the other engagement element—the element being subjected to a force—couples with one of the abutments of the rotatable actuating element, whereby the abutment of the twist handle—the abutment being subjected to a force—and the abutment of the actuating element—the abutment being subjected to a force—are facing in opposing directions of rotation. Consequently, the abutments bias the torsion spring when the actuating element cannot follow a direction of rotation of the twist handle in a synchronous manner. In an inoperative position, the torsion spring may also be biased in both directions. As a result of this, the switching force may be increased.
One embodiment provides that one of the engagement elements couples only with the abutments of the twist handle and the other engagement element couples only with the abutments of the actuating element, or that one of the engagement elements couples only with abutments that face in the positive direction of rotation and the other engagement element couples only with abutments that face in the negative direction of rotation.
The engagement elements may have a radial extension that extends from the axis of rotation over at least the first distance and the second distance. The abutments of the twist handle may be arranged at a first distance from the axis of rotation, the abutments of the rotatable actuating element may be arranged at a second distance from the axis of rotation, whereby the first distance and the second distance are different from each other.
Considering a further embodiment, the engagement elements delimit a continuous sector of a circle relative to the axis of rotation, whereby all the abutments are arranged within the sector. In a synchronous position, respectively one of the abutments of the twist handle and one of the abutments of the actuating element abut against one of the engagement elements and the other abutment of the twist handle and the other abutment of the actuating element abut against the other engagement element.
Another development is characterized by a rotatable bearing that has a hollow hub and a pin that is inserted into the hollow hub so as to be rotatable. Either the hollow hub may be configured as a part of the twist handle and the pin as part of the rotatable actuating element, or the hollow hub may be configured as part of the rotatable actuating element and the pin as part of the twist handle. The twist handle and/or the rotatable actuating element may be fabricated in one piece as injection-molded parts. As a result of this, a simple and compact design of the rotary switch can be achieved.
Considering a tool machine having at least two different drive modes, an axially shiftable clutch may be provided for switching between the drive modes. A selector switch is configured as the inventive rotary switch, whereby the eccentric of the switch is coupled with the clutch. The switching paths or the distance of the eccentric from the axis may be configured in such a manner that—in the desired switching positions—a connecting line between the eccentric and the axis is parallel to the axial switching path. Consequently, the selector switch and the spring may be disengaged due to forces acting in axial direction.
In a further development of the tool machine, the eccentric is coupled with the clutch by means of a sleeve-shaped switching rod assembly. The tool machine may have a cylinder-shaped drive arrangement, whereby the sleeve-shaped switching rod assembly circumscribes the drive arrangement. The sleeve-shaped switching rod assembly ensures high mechanical stability. The switching rod assembly may be supported so as to be rotatable about an axis of symmetry relative to the clutch. The switching rod assembly and the clutch may be configured so as to come into ring-shaped engagement with each other for axially shifting the clutch by means of the switching rod assembly. Consequently, the switching rod assembly can actuate the clutch, independently of the rotary position of the clutch. At the same time, the ring-shaped engagement ensures a uniform application of force in order to prevent warping.
The tool machine may comprise a percussion drive and a rotary drive for a tool, whereby the clutch selectively couples the percussion drive and/or the rotary drive with the tool. In particular, the tool machine may be a hand tool machine, a combination hammer.
The description hereinafter explains the invention with reference to exemplary embodiments and the figures.